A printing device capable of double printing on a thermal paper and a passbook has been developed and commercialized.
Such printing device may include a plurality of printing units each operating in response to commands provided from a host computer.
A system including two printing units may operate such that the two printing units are controlled by commands from a higher-level host computer.
However, a printing device having a plurality of printing units as mentioned above has some drawbacks. Due to the use of a single controller in controlling all the printing units, the printing performance degrades with an increase in printing data, such as graphic data. To alleviate this drawback, a controller having improved control performance needs to be used. However, such controller is costly, and accordingly the manufacturing costs of the printing device increase.